3 Hormones That Intensely Control Human Behavior & Mindblowing Studies
I recently stumbled upon Robert Sapolsky’s “Behave: The Biology of Humans at Our Best and Worst” and was immediately hooked on the sheer amount of information our brain processes every second. In the first chapters, he discussed the basics of our brain and how the approximately one hundred billion neurons in our brain communicate with each other and form complex circuits.
Robert continues to take you through a vivid journey, from explaining interesting and crucially important parts of the brain (duh, aren’t all parts of importance?) to the triggers and pathways that activate these parts.
I will be quoting much from the book in this article, so my deepest respect and appreciation go to Robert Sapolsky.
Hormones & Neurotransmitters
A hormone is a chemical messenger released by secretory cells (including neurons) in various glands. Once released, it enters the bloodstream where it can affect all cells in the body that have receptors for it.
However, hormones do not determine, command, cause or invent behavior, instead, they make us more sensitive to the social triggers of emotionally charged behaviors and reinforce our pre-existing tendencies in these areas.
On the contrary, neurotransmitters like dopamine for example directly affect only the neurons on the other side of the synapses, while a hormone can potentially affect any of the trillions of cells in the body.
Neurotransmitters that signal hormonal effects occur over hours to days and can last forever. This is because synapses are bridged in milliseconds. In contrast, puberty often disappears after some time.
To shed some light on the title we are going to take a closer look at Testosterone, Oxytocin and Vasopressin.
Testosterone
Testosterone has far less to do with aggression than most assume.
Within the normal range, individual differences in testosterone levels do not predict who will be aggressive. The more an organism has been aggressive, the less testosterone is needed for future aggression.
If testosterone plays a role, it is a facilitating one — testosterone does not “invent” aggression. It makes us more sensitive to aggression triggers, especially those most prone to aggression.
When testosterone rises after a challenge, it does not cause aggression, instead, it triggers all the behaviors needed to maintain status. This changes things enormously.
Well, maybe not, because status maintenance in male primates consists mainly of aggression or the threat of aggression — from slashing an opponent to a “you have no idea who you’re messing with” look.
What happens when defending one’s status requires being nice though?
This was investigated in a study by Christoph Eisenegger and Ernst Fehr of the University of Zurich. Participants played the ultimatum game, in which you decide how to divide the money between yourself and another player.
The other person can accept or reject the split, in which case neither of you gets anything. Previous research has shown that someone whose offer is rejected feels rude and outclassed, especially if word gets out in future rounds with other players.
In other words: In this scenario, status and reputation are based on being fair.
And what happens if the subjects were given testosterone beforehand?
People made more generous offers.
What the hormone does depends on what is considered masculine. This requires sophisticated neuroendocrine wiring that responds to social learning. There are few results that contradict testosterone’s reputation more. In another experiment, subjects were given either testosterone or saline without knowing which.
Subjects who believed it was testosterone (regardless of whether it actually was testosterone) made less generous offers. In other words, testosterone doesn’t necessarily lead to bad behavior, but the belief that it does and that you’re drowning in the stuff leads to bad behavior.
Other studies show that testosterone promotes prosociality in the right environment. In one such study, testosterone reduced men’s cheating at a game under circumstances where feelings of pride depended on honesty.
In another study, subjects decided how much of a sum of money they would keep and how much they would publicly contribute to a common pool shared by all players; testosterone made most subjects more prosocial.
What does it mean?
Testosterone makes us willing to do whatever it takes to gain and maintain status. And the key point is what it takes to do that.
If you get the social circumstances right and raise testosterone levels during a challenge, people will compete like crazy to do the most random acts of
kindness.
In our world dominated by male violence, the problem is not that testosterone can raise aggression levels. The problem is the frequency with which we reward aggression.
Oxytocin & Vasopressin
Both occur naturally in the mammalian body and play a role in pair bonding, orgasms, maternal bonding, group and anxiety behaviors, among others.
Oxytocin and vasopressin facilitate the formation of mother-infant bonds and monogamous pair bonds, reduce anxiety and stress, enhance trust and social belonging, and make people more cooperative and generous.
In biting terms, oxytocin makes people irrational fools; in more angelic terms, oxytocin makes people turn the other cheek.
Other prosocial effects of oxytocin have been noted. It caused people to better recognize happy (as opposed to angry, fearful, or neutral) faces or words with positive (as opposed to negative) social connotations when they were briefly displayed. In addition, oxytocin made people more benevolent.
People with the version of the oxytocin receptor gene associated with more sensitive parenting were rated by observers as more prosocial (when talking about a time of personal suffering) and were more receptive to social recognition. And the neuropeptide made people more receptive to social reinforcement by increasing performance on a task in which correct or incorrect answers elicited a smile or a frown, respectively (whereas it had no effect when correct and incorrect answers elicited different colored lights).
So oxytocin triggers prosocial behavior, and it is released when we experience prosocial behavior (when we are trusted in a game, when we receive a warm touch, etc.). In other words, a warm and cuddly positive feedback loop.
Apparently, oxytocin and vasopressin are the greatest hormones in the universe. Feed them into the water supply and people will be more charitable, trusting and empathetic. We would be better parents and make love instead of war (especially platonic love, since people in relationships, would give everyone else a wide berth). And best of all, we would buy all kinds of useless crap, relying on the banner ads in stores.
Furthermore, oxytocin caused men in relationships to spend less time looking at pictures of attractive women. Importantly, oxytocin did not cause men to rate these women as less attractive; they were simply less interested.
So oxytocin and vasopressin facilitate bonding between mother and child and between couples.
Another fun fact:
When a dog and its owner (but not a stranger) interact, they release oxytocin.
The more time spent staring at each other, the greater the increase. If you give dogs oxytocin, they stare at their humans for longer… which increases people’s oxytocin levels.
Consistent with its effects on bonding, oxytocin inhibits the central amygdala, suppresses fear and anxiety, and activates the “calm, vegetative” parasympathetic nervous system.
The amygdala is a part of the brain and has a dual role with aggression as well as with facets of fear and anxiety. Fear and aggression are necessarily intertwined — not all fear causes aggression, and not all aggression has its roots in fear.
In addition, people with an oxytocin receptor gene variant associated with more sensitive parenting also have a lower cardiovascular startle response.
Vasopressin increases aggression in paternal prairie mouse males. This result is associated with a known additional condition. The more aggressive the male prairie vole, the less aggression decreases after blocking the vasopressin system — just as with testosterone, aggression is maintained with experience by social learning rather than by the hormone/neuropeptide.
Vasopressin also increases aggression, especially in male rodents that are already aggressive — another biological effect that depends on individual and social context.
Interestingly, oxytocin promotes trust and cooperation in an eco game — but not when the other player is anonymous and in a different room.
When playing against strangers, oxytocin decreases cooperation, promotes envy when you’re unlucky, and increases schadenfreude when things go well.
Finally, nice studies by Carsten de Dreu of the University of Amsterdam showed how unsympathetic and fuzzy oxytocin can be.
In the first study, male subjects formed two teams; each subject decided how much of his money to put into a pot shared with teammates. As usual, oxytocin increased this generosity. Then participants played the “Prisoner’s Dilemma” with someone from the other team.
If the financial stakes were high, which motivated the subjects, oxytocin increased the likelihood that they would preemptively stab the other player in the back.
So overall, oxytocin makes you more prosocial toward your peers (i.e., your teammates), but spontaneously lousy toward others who pose a threat.
As De Dreu points out, oxytocin may have evolved to improve social skills so we can better identify who is a “we”.
In case you’re not familiar with the trolley problem:
In the classic version, there is a trolley on a track heading towards five people who are unable to move out of the way. You are standing by a lever that can divert the trolley onto a different track with only one person.
You must choose whether to divert the trolley, killing one person to save five, or do nothing and allow the trolley to continue on its current course, killing five people. Most people (roughly 80%) would pull the lever.
However, things look a lot different, when the only way to stop the trolley is to push someone off a bridge on the tracks. Only 10% are willing to do that.
Further studies from the Netherlands show that if you raise the oxytocin level of your test subjects, they are more willing to push an Otto or Mohammed on the rails, rather than a dutchman (one of their own).
Final Words
Hormone/neurotransmitter similarities continue. Like neurotransmitter receptors, a hormone receptor’s “avidity” for its hormone can change. This means that the shape of the binding site changes a bit, so that the hormone now fits more or less snugly, thus increasing or decreasing the duration of the hormone’s effects. The number of receptors for 2 particular hormones in a cell can also change, altering the cell’s sensitivity to that hormone’s effects.
Finally, receptors for a hormone typically occur in only a subset of cells and tissues in the body, meaning that only those are responsive to the hormone. I hope this gave you some insight into the complexity of hormones and how they function. I think it’s simply interesting to know what’s happening with us in certain situations, where the behavior came from.
I will continue this behavior series with a deeper dive into some parts of the brain so stay tuned for more and thanks for reading.
—
Subscribe to my newsletter to receive similar content directly to your inbox.
I sincerely hope my posts impacted your life in positive ways!
https://robinklose.medium.com/subscribe
Since I don’t get paid by Medium directly, it would mean the world to me if you could check out https://ko-fi.com/robink1 and maybe even buy me a coffee with a small tip!
Every amount is greatly appreciated, especially if you leave a kind note at the end :)
